Petiole 15--100 cm. Blade broadly triangular to sometimes ovate, 3-pinnate or 3-pinnate-pinnatifid at base, 20--80 × 25--50 cm; blade margins and abaxial surface shaggy, rachises and costae glabrous or sparsely pilose abaxially. Pinnae (proximal) broadly triangular, distal pinnae narrowly triangular or oblong; terminal segment of each pinna ca. 2--4 times longer than wide, longer ultimate segments less than their width apart, ca. 3--6 mm wide. Pinnules at 45°--60° angle to costa; fertile ultimate segments adnate or equally decurrent and surcurrent. Outer indusia entire or somewhat erose, glabrous. 2 n = 104. In barrens, pastures, open woodlands in moderately to strong acid soil, abundant, forming large colonies; 0--1500 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld., N.S., P.E.I., Ont., Que.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Pa., R.I., S.C., S.Dak., Tenn., Vt., Va., W.Va., Wis.; Mexico in Nuevo León; Europe; Asia. Colonies are more frequent in the northern part of the range. Fertile colonies, however, are more frequent in the southern and eastern portion of the range. Outliers in British Columbia and Alberta, which we have not seen, are documented in W. J. Cody and D. M. Britton (1989).
Longest entire lf-segment or part of a segment ca 4 times as long as wide, the terminal segments mostly 5-8 mm wide; margins of the ultimate segments commonly somewhat hairy; throughout our range, and also in Eurasia
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.